Multitube falling film reactor for the continuous manufacturing of sulfonated and/or sulfated compounds

ABSTRACT

Multitube falling film reactor (MTR) for continuous manufacturing of sulfonated and/or sulfated products using gaseous, diluted sulfur trioxide, (SO 3 (dil)) to produce surface active agents or simply surfactants, useful in the cosmetic and detergent industry. Each individual nozzle-set comprises a male part (19) and the other half (45) on the male part (10). The male part (10) forms together with the female part (19), an annular slot (21) with a constant and under all operational conditions well defined length (47), which together with a fixed opening/width determines the individual pressure drop of the said slot and thereby the individual organic flow. With this arrangement, completely homogenous distribution of organic feed is achieved without the necessity of calibration.

This application is the U.S. national stage application of Internationalapplication Ser. No. PCT/NO/00065, filed Mar. 22, 1996, which is acontinuation of Norwegian application Ser. No. 95.1178, filed Mar. 28,1995, and claims the benefit of the filing dates thereof under 35 U.S.C.§119.

BACKGROUND OF THE INVENTION

Multitube falling film reactors represent today a well establishedtechnology, and is frequently the preferred reactorprinciple forsulphonation and sulphation reactions, both giving advanced products;surfactants for the cosmetic and detergent industry. The reactors areassembled according to conventional principles for a multitube shell andtube heat-exchanger with different baffle-arrangements and coolingliquids, with water as the dominating cooling liquid. Typical for allreactors are separate chambers for diluted gas, organic compound,cooling liquid and collection of finished products, chambers mentionedfrom top of reactor to bottom outlet.

When producing surfactants for the said industry, the gaseous anddiluted reactant is sulfur trioxide, typical organic compounds areliquids at 15° C. or higher, the main variety of raw-material beingalkylates, fatty alcohols, etoxilated fatty alcohols, alpha-olefins andmethyl-esters. Any chemical compound equipped with a socalled flexiblehydrogen atom might be sulphonated or sulphated. (Sulphated for allcompounds where hydrogen is linked to an oxygen atom, sulphonated forthe linkage hydrogen-carbon.)

The overall chemical reactions taking place, are characterized by thefact that diluted, gaseous SO₃ is a very aggressive/reactive reactant,and that the reactions are all extremely rapid and exothermic.Altogether, these properties challenge the control of the molar ratiobetween the reactants, and only with the very best control of both totaland local molar ratio, the best products are achieved. Any deviation inthe molar ratio will unavoidably result in increased quantity ofundesired by-products, and the main product will suffer from bad colour,lower active matter content, higher content of sulphates, higher contentof nonsulphated/-sulphonated organic compounds and consequently loweryield with a higher raw-material consumption. In a MTR, where thenumbers of individual and parallel reactor-element could be from two tomore than hundred, the most important parameter is the local molar ratiobetween the reactants, and therefore the best possible and mosthomogeneous distribution of organic compound to each individualreactor-element. Even the smallest deviation in local molar ratio, cannot be fully compensated for later in the process.

To avoid any misunderstanding, total molar ratio is defined as the ratiobetween the total number of moles SO₃ fed to the reactor divided by thetotal number of moles organic compound fed to the same reactor. Byadvanced dosing system for liquid sulfur/liquid sulfur dioxide/liquidsulfur trioxide and finally organic compounds, the total molar ratio canbe kept almost constant and without any significant impact on the finalproduct properties.

The local molar ratio, defined the same way but between local flows ofsaid reactants for each individual nozzle-element, is predominantlydepending on an even and homogeneous feed, kg/hour of organic reactantto each individual nozzle-set from one common, organic chamber, since agas carrying a far lower viscosity has a higher tendency of evendistribution according to the principle of "the way of lowestresistance". The nozzle-set construction will therefore appear as thedecisive and critical element for individual organic flow and localmolar ratio. In a MTR, all the nozzle-sets are fed from one common,organic chamber. The nozzle-construction also allows a reactor toconsist of only one reactor element, where the total molar ratio becomesequal and identical to the local molar ratio, accuracy only depending onthe external dosing system.

Of great and vital importance is also an even and homogeneousdistribution of the organic film formed circumferentially on theinternal, surface of the female part. This can be achieved, providedthat the film distribution/formation on the internal surface of the saidfemale part is determined by the same accuracy as the dosing/metering oforganic compounds of the nozzle-set for all reactor elements. It meansaltogether that the film-formation should be determined by the sameaccuracy as the dosing/metering of organic compounds, i.e. a welldefined annular slot in respect of length an width for all known,operational conditions.

There are several, different concepts of constructions available on themarket and already patented, relevant in this connection are followingpatents:

U.S. Pat. No. 3,918,917 Nitto Chemical Industry Co., Ltd.

U.S. Pat. No. 4,183,897 Construzioni Meccaniche G. Mazzoni S.p.A

FR 2,449,665 Ballestra Chimica S.p.A

EP 0,570,844 A1 Meccaniche Moderne S.r.l

These patents and constructional concepts can be described and groupedby following:

precalibrated and selected/grouped orifices (materials totally differentfrom this patent), characterized by a relatively long distance betweenthe zone for metering/dosing and the zone for film formation.(Pre-selected/grouped orifices should not be mixed up with theterminology nozzle-set and nozzle-set construction described in thisdocument.)

conical or cylindrical slots where even a lower accuracy (compared tothis invention) of organic feed only can be achieved through amechanical adjustment of the slots length or opening by shims. If theslot opening and slot length were well defined in these constructions,and besides appeared with the accuracy described in mentioned patents,no adjustment by shims would be necessary. It is obvious that thelocation of the male part relatively to the female part by shims, willbe influenced by different pressure working on the mainflanges/cylindrical plates(pressures different from the conditionsduring calibration), by the torque on single bolts for tightening, bysealing material and finally by the distance between the cylindricalplates. The fact that all individual nozzle-sets have to be calibratedbefore start-up, also clearly demonstrates the unsufficient definitionof the opening and length of the slots, resulting in a less homogeneousdistribution of the film (different thickness around the wettedperiphery) on the internal surface of the female part of the nozzle-set.

The main differences/disadvantages for already known and operativeconstructions compared to the nozzle-set construction described in thisdocument, can be summarized by following:

higher tendency of air-pockets and thereby partly blocking of organicfeed during start-up. (Air-pockets in the space between male and femalepart of the nozzle-set.)

partly more complex components, less easy to machine.

need for time-consuming calibration both before start-up and after anuncontrolled stop during operation, or after a routine washing/cleaningprocedure. The accuracy of this calibration will also be influenced bythe fact that normal plant conditions are always different fromcalibration conditions.

generally lower accuracy for individual organic feed compared to thetotal average of organic feed for all nozzle-sets in operation.

generally will lower accuracy of metering mean increased variation infilm thickness.

tightening arrangement for the male and female part of the nozzle-setwill influence the accuracy of individual nozzle-set supply and alsosaid accuracy for neighbouring nozzle-sets.

the neccessity of shims adjustment creates very frequently tendency ofincreased leakages.

accuracy of metering will strongly depend on the torque applied fortightening the bolts.

the individual supply from each nozzle-set will further also bedepending on pressure variations during normal operation, pressuresworking on the different cylindrical plates and giving different impactdepending on the location of the nozzle-set on the said plates.

DESCRIPTION OF THE INVENTION Summary of the Invention

The nozzle-set represents the most vital component/part of any multitubefalling film reactor, and this invention relates mainly to the design,construction and assembling of all the individual components comprisinga nozzle-set.

The nozzle-set reported in this document, is characterized by a welldefined annular slot having a fixed length and a fixed width under allknown operational conditions.

The necessity of complicated and less reliable arrangement forcalibration like shims etc is eliminated, and the invented nozzle-setwill also give a substantial increase in the homogeneity of the filmthickness. There is no need for calibration before start-up, ortime-consuming re-calibration after a stop in the plant.

A model of the reactor with more than 30 parallell nozzle-sets in fullsize have been tested, and by introducing the average flow x_(av),g/min, for all nozzle-sets, all individual flows are covered by therange:

    x.sub.av ±0.2%

An accuracy level like this, has uptil now not been reported, and thereactor with the new nozzle-set will be named the NCN reactor, whichmeans: No Calibration Needed.

The NCN nozzle-set may be installed in all MTR reactors designed forheterogene reactions, even for reactions where for instance reactiveparticles are present and suspended in an inert liguid, (inert to thegaseous reactant).

ATTACHED FIGURES AND DEFINITIONS/TERMINOLOGY

FIG. 1 is a longitudinal section of a complete and assembled multitubefalling film reactor Type NCN, with three individual nozzle-sets fixedto reactor-tubes partly in section.

FIG. 2 is a detailed assembly drawing for one complete nozzle-setcomprising a female part, a male part, respective tighteningarrangement, tightening bolts and sealing system all arrangend on twoindividual and separated cylindrical plates.

FIG. 3 is a cross section of FIG. 2 A--A enlarged, and shows in detailthe six channels for liquid,organic feed to the expansion chamber.

Nozzle-set: A complete unit comprising a female part, a male part,respective tightening arrangement, tightening bolts and sealing system.

Reactortube: A conventional tube, total length 5-7 m, and fixed to thefemale part of the nozzle-set. The reactortube represents in this waythe zone for the chemical reaction taking place, and transfers heat ofreaction to the surrounding and circulating cooling liquid.

Reactor-element: A complete unit having as integral parts onenozzle-set, one reactortube and finally sealing arrangements.

Multitube falling film reactor, FIG. 1: A complete reactor unitincluding from two to more than hundred reactor-elements together withseparate chambers for distribution of gaseous reactant, liquid organicreactant, cooling liquid, collecting chamber for finished product andconnections for all material flows.

Reactorhead: Includes the nozzle-sets and the organic chamber definedand limited by a cylindrical plate fixed to a cylindrical spacer fixedto a counter-flange bolted and sealed to the lowest cylindrical plate.

Calibration of nozzle-set: Manual and time-consuming work for allindividual nozzle-sets, at least the reactorhead must be fully assembledto accomplish this procedure. A quantity of organic reactant normallycorresponding to the nominal capacity of the reactor, is fed to thecommon organic chamber, and all the individual flows leaving nozzle-setsor reactortubes, are carefully determined by weighing. Based on themeasuring results from this procedure, an aritmetic average for theindividual flows is calculated, for instance X_(av). Any deviationoutside a predetermined and acceptable range, will have to be adjustedfor by replacement of the shims having thicknesses different from theones originally installed. Normally this procedure will have to berepeated uptil several times to reach a range described by:

    X.sub.av ±1.0%

For reactortechnology of yesterday, average ±2.5% is quite usual andrather seldomly average ±1.0% is reached. Unfortunately, the samereactortechnology can neither confirm nor guarantee this range/limit ofdeviation during normal, operational conditions.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the attached figures, FIG. 1, FIG. 2 and FIG. 3,together with the definitions and terminology listed in para 3, acomplete, multitube falling film reactor vil include more than tworeactor-elements in parallell, chamber 4 for distribution of the gaseousreactant, chamber 11 for distribution of organic reactant, chamber 25for cooling liquid and chamber 53 for collecting of finished product,chamber 53 being defined by plate/flange 29/31 and the conical bottomcap 32, all mentioned parts from reactor top to reactor bottom/outlet.All the chambers are separated from neighbouring chamber withplates/flanges 8, 9, 16, 18, 27, 29 and 31, sealing systems, outercylindrical mantle and conical caps 3/32 at top and bottom respectively.At the outlet of each reactor-element, stuffing-boxes 28/30 installed inplate 29 efficiently prevent leakage between cooling-chamber 25 andcollecting chamber 53. These stuffing boxes allows thermal, longitudinalexpansion of reactor-tubes during normal plant conditions/operation.

The upper chamber 4 being fed through 1 and limited by a conical top cap3 and the upper plate 9 together with the flange 8, evenly distributesthe gaseous reactants to all individual reactor-elements.

Liquid, organic reactant being fed from a central pipe-line anddistributed to the organic chamber 11 through several feeding-tubes 12.This chamber 11 is also equipped with a on/off ball-valve forde-areation during start-up and operation. The chamber 11 is vented tothe surrounding atmosphere. The operating pressure in chamber 11 isgiven by the pressure drop through the annular slot 21 and the gaspressure in the reactortube 24.

Liquid, organic reactant is fed from the common chamber 11 to eachseparate nozzle-set at 13 along the total periphery of female part 10and further to the expansion-chamber 20 through the longitudinal feedingchannels FIG. 2/FIG. 3 40. The organic reactant is perfectly metered anddistributed through the annular slot 21 forming a continuous and uniformfalling film 50 on the internal surface of the female part 19. At theoutlet of the slot 21, the liquid organic reactant from chamber 11 meetsthe gaseous reactant from chamber 4, immediately starting the exothermicand heterogeneous chemical reaction. The heat of the reaction istransferred to the outer surface of the reactor-tube, and continuouslyremoved by the circulating cooling liquid in chamber 25. The coolingliquid fed to the same chamber through 26, leaving at 22. The finishedproduct from all reactor-elements is collected at the bottom of thereactor in chamber 53, leave at 34 and further downstream treated in aspecial separator/cyclone for the separation of gas/liquid.

The complete nozzle-set will according to this document include a malepart 10, a female part 19, tightening arrangements 5/6 and 14/15respectively, and sealings 7/17 respectively.

Female part 19 equipped with integral tightening flange 41, is fixed tothe plate 18 by the tightening ring 15 and two-four bolts 14. Thecylindrical plate 18 separates the organic chamber 11 from the coolingchamber 25. The integral flange on female part 19 has an heigth equal tothe depth of the tightening-ring 15 at 43, thus forming a completelyeven surface and together with sealing 17 comprise a sealing systembetween the female part 19 and the plate 18. Built-in distance/clearance42 between the said female flange 41 and the said tightening ring 15,efficiently prevents radial forces to occur and acting on the femalepart 19 through 41.

The position of the female part 19 is according to above only determinedby the cylindrical opening in plate 18. Longitudinally, the position isdetermined by the applied torque on the bolts 14, sealingthickness/compressibility and additionally by different pressure- andtemperature-conditions during operation. A cylindrical section/spacerbetween flange 16 and upper plate 9 forms together with the lower plate18 the said organic chamber 11. To avoid eccentrisity between plate 9and 18, plate 18 is equipped with at least two conical guiding pinsentering corresponding holes in flange 16 with a high degree ofprecision.

The female part 19 is internally machined forming one half 44 of theexpansion chamber 20. This machined part 44 of the expansion chamber 20is identical to the other machined half 45 located at the outer surfaceof the male part 10. Together the two halves comprise the said expansionchamber 20. The female part 19 is fixed to the reactortube 24, length5-7 m, at 23.

The male part 10 is equipped with a similar, integral flange 38 with theheight corresponding to the depth of the tightening ring 6 at 35.Together, flange 38 and ring 6 form a completely even surface andtogether with sealing at 7 comprises a sealing system between the malepart 10 and the plate 9. Built-in distance/clearance 37 between the saidmale flange 38 and the said tightening ring 6, efficiently preventsradial forces to occur and acting on the male part 10 through 38. Thesaid tightening ring 6 is equipped with oversized holes for bolts. Incombination with the said clearance 37, the clearance between the holesin the plate 9 and male part 10, the said oversized holes 36 efficientlyprevent any radial forces to occur and act on the said flange 38 nor thetotal male part 10 of the nozzle-set. The important centering of themale part 10 into the female part 19, is according to above onlydetermined by the guiding zone 52.

Longitudinal channels 40 machined on the outer surface of the male part10, leeds the organic feed from the chamber 11 to the expansion chamber20.

The size and number of these channels are carefully selected to givemaximum guiding surface in combination with low, lineaer velocity of theliquid making this nozzle-set self-deareating during start-up andoperation. Self-deareating as terminology is concequently applied forany gaseous component being present before start-up and/or dispersedgasparticles in the bulk flow of organic that might occur during normaloperation. The male part 10 of the said nozzle-set is externallymachined to form one half 45 of the expansion chamber 20. Characteristicfor this invention and construction is that both the length 47 and theopening of the annular slot 21 is defined once for all and under allknown operational conditions, provided that the lower lips 48 and 49 ofthe halves 44 and 45 respectively under the said conditions always willbe separated a distance 46 and with the lip 49 at the lower position.The feed of organic liquid to or from the nozzle-set, will according tothis invention only depend on the channel length 47 which is welldefined for all nozzle-sets and constant opening of the annular slot 21formed between the male and female part. The said distance 46 betweenthe said lips 48 and 49, will be determined according to followingrelation:

The length of half-chambers 44 and/or 45 in expansionchamber20 >distance 46>0 The lip 49 always located at the lower position of thetwo lips 48 and 49

The distance 46 between lip 48 and 49 being normally 2.0-3.0 mm, willpermanently and automatically compensate for all sorts of externalforces tending to move in longitudinal direction the male part 10relatively to the female part 19 or opposite.

The pressure drop in the annular slot 21 determines the flow from eachnozzle-set, and with the annular slot being constant even when maleparts moves relatively to the female part or opposite (limits stated inabove relation), the same pressure drop will remain constant and finallythereby the flow.

In other words, for any complete nozzle-set equipped with a constantslot opening 21, the flow will remain constant as long as the distance46 is within the limits of said relation and thus giving a constant slotlength 47 indepent of variations in operational conditions. Thenozzle-set will permanently need no mechanical arrangements foradjusting the relative position of male and female part to influence oradjust the individual flows, and there will be no need neither forcalibration nor re-calibration.

The invention therefore comprises a multitube falling film reactor witha nozzle-set as described in details above, showing an uptil now unknownaccuracy and without the necessity of complicated and less reliablemechanical arrangements for final adjustments of all individual flows.Additionally, any need for calibration before start-up, orre-calibration in connection with uncontrolled stops and routinemaintenance, is eliminated compared to other, similar constructions.

The invention has been described according to one embodiment of theinvention, and alternatives may be made by one skilled in the art. Theinvention embraces all such alternatives which are clearly in family toand within the spirit and protective scope of the following claims.

I claim:
 1. A multi-tube falling film reactor for the continuoussulphonation and sulphation of a liquid organic substance by reactionwith gaseous SO₃, comprising: at least two reactor elements, eachelement consisting of a nozzle set comprising an inner male portion andan outer female portion, which portions are in their respective upperpart provided with an integral flange device for mounting to a firstchamber plate and a second chamber plate, respectively, the femaleportion is in its lower part connected to a reactor tube which in itslower part is mounted to a third chamber plate, whereby each reactorelement is fed with an organic substance from a common organic chamberthrough longitudinal channels defined on the outside of the male portionand via an expansion chamber and further down in the reactor tubethrough an annular channel formed between the outer circular surface ofthe male portion and inner circular surface of the female portion of thenozzle, the organic substance reacts with the SO₃ gas which flows downin the reactor tube through the inner bore of the nozzle from a commongas distribution chamber, the reactor tube and the lower part of thenozzle are further arranged inside a common cooling chamber whereby theresulting product from all reactor elements is collected in a collectingchamber at the bottom of the reactor, wherein the longitudinal channelsare extended along the complete contacting/guiding surface between theouter surface of the male portion and the inner surface of the femaleportion of the nozzle, respectively, characterized in that the expansionchamber is formed as a circumferential groove/milling in the outercircumferential surface of the male portion and that the height of theannular channel between the outer surface of the male portion and theinner surface of the female portion, and thereby the volume of theannular channel itself, is constant with respect to axial displacementof the male portion inside the female portion and thereby every reactorelement will maintain a constant flow rate under varying processconditions.
 2. Reactor according to claim 1, characterized in that theexpansion chamber (20) in the various reactor elements are formed bycooperation between said groove (45) in the outer circumferentialsurface of the male portion (10) and a circumferential groove/milling(44) in the inner circumferential surface of the female portion (19) ofsimilar volume as the groove (45) in the outer circumferential surfaceof the male portion (10), the lower circumferential edge (49) of thegroove (45) of the male portion (10) during operation having adisplacement (46) in relation to and located below the lowercircumferential edge (48) of the female portion (19), the displacement(46) is larger than zero and less than the height of each groove (44,45).
 3. The reactor according to claim 1, characterized in that a numberof longitudinal channels are six.
 4. The reactor according to claim 3,characterized by one of the two reactants being present as gaseousreactant and the other participating reactant present as a liquid atambient temperature or temperatures corresponding to the reactionconditions, the said reactor assembled as a conventional multitube shelland tube heat exchanger with separated chambers for gaseous reactant,liquid organic reactant, cooling liquid and collection of finishedproducts.
 5. The reactor according to 4, characterized by furthercomprising a plurality of nozzle-sets, from two to more than hundred,and where the said liquid organic reactant is fed to the common organicchamber through a plurality of separated feeding tubes, the organicchamber being defined by cylindrical plates and, counterflange andfinally cylindrical spacer fixed and welded to plate and flange, adiluted gaseous reactant is further fed to the common chamber limited byflange, cylindrical plate and conical top cap, and that finished productare collected in chamber defined by a conical cap, cylindrical plate andcounterflange, the cylindrical plate equipped with stuffing boxes forreactor tube and arranged at the reactor bottom/outlet.